Money.
You can send a shipment (17x10x1 cm and 250 gr) by National regular parcel for $15.81 and delivery should be in eight BUSINESS days.
Or you can send it by National Priority Post for $56.67 and it should arrive in two Business days.
https://www.canadapost-postescanada.ca/cpotools/apps/far/business/findARate?execution=e1s4
Or you could send it LetterMail for $4.40 and delivery should be within eight days.
https://www.canadapost-postescanada.ca/cpc/en/personal/sending/parcels/compare-services-canada.page?
Generally Canada Post is the cheapest service and ships everywhere in Canada. Couriers often sub-contract to Canada Post for shipments to rural or isolated locations.
If your customer is demanding faster service than you trust your shipper to provide, it is better to refuse the transaction. Dealing with bullies does not get better.
